Rear projection type image display device

1. A rear projection type image display device comprising: an illumination optical system for irradiating an image display element with a light from a light source; and a projection optical system for projecting an image on the image display element onto a screen; wherein: the illumination optical system includes a first fly-eye lens dividing a light emitted from the light source, a polarization beam splitter monopolarizing the light beam divided by the first fly-eye lens, a second fly-eye lens irradiated with a light beam monopolarized by the polarization beam splitter, a field lens irradiating the image display element with a light beam output from the second fly-eye lens, a first dichroic mirror separating the light beam irradiated from the field lens into a red light beam and a cyan light beam, a first image display element irradiated with the red light beam separated by the first dichoric mirror and a first lens providing a trimming filter with a spectral reflection characteristic, the first lens being disposed in an optical path from the first dichroic mirror to the first image display element, and the projection optical system includes first and second lens groups disposed in this order in an optical path from the image display element to the screen so as to obtain enlarged images twice or more, the first lens group positioned closest to the image display element being in a substantially telecentric relation to the image display element side, the first lens group forming a first enlarged image on the image display element side with respect to the second lens group and the second lens group having a positive refracting power and a filed angle of not smaller than 90 degrees.

2. A rear projection type image display device according to claim 1 , wherein the illumination optical system includes a second dichroic mirror possessing a characteristic of reflecting light of green region, a second image display element irradiated with the green light beam reflected by the second dichroic mirror and a second lens providing a trimming filter with a spectral reflection characteristic, the second dichroic mirror being disposed in an optical path of the cyan light beam separated by the first dichroic mirror and the second lens being disposed in an optical path from the second dichroic mirror to the second image display element.

3. A rear projection type image display device according to claim 2 , wherein the illumination optical system includes a first reflecting mirror reflecting a blue light beam transmitted by the second dichroic mirror, a third lens irradiated with the blue light beam reflected by the first reflecting mirror, a second reflecting mirror reflecting the blue light beam irradiated from the third lens, a fourth lens irradiated with the blue light beam reflected by the second reflecting mirror and a third image display element irradiated with the blue light beam from the fourth lens, the first fly-eye lens and the third lens providing a UV cut-off filter and at least one of the first reflecting mirror, the second reflecting mirror and the fourth lens providing a characteristic of a dichoric mirror.